.\" zip_source_seek_compute_offset.mdoc - validate arguments and compute offset
.\" Copyright (C) 2014-2017 Dieter Baron and Thomas Klausner
.\"
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.Dd December 18, 2017
.Dt ZIP_SOURCE_SEEK_COMPUTE_OFFSET 3
.Os
.Sh NAME
.Nm zip_source_seek_compute_offset
.Nd validate arguments and compute offset
.Sh LIBRARY
libzip (-lzip)
.Sh SYNOPSIS
.In zip.h
.Ft zip_int64_t
.Fn zip_source_seek_compute_offset "zip_uint64_t offset" "zip_uint64_t length" "void *data" "zip_uint64_t data_length" "zip_error_t *error"
.Sh DESCRIPTION
Use this function to compute the offset for a
.Dv ZIP_SOURCE_SEEK
or
.Dv ZIP_SOURCE_SEEK_WRITE
command.
.Ar data
and
.Ar data_length
are the arguments to the source callback,
.Ar offset
is the current offset and
.Ar length
is the length of the source data or, for
.Dv ZIP_SOURCE_SEEK_WRITE ,
the amount of data written.
.Sh RETURN VALUES
On success, it returns the new offset, on error it returns \-1 and
sets
.Ar error .
.Sh ERRORS
.Fn zip_source_seek_compute_offset
fails if:
.Bl -tag -width Er
.It Bq Er ZIP_ER_INVAL
One of the arguments is invalid or the seek would place the offset
outside the data.
.El
.Sh SEE ALSO
.Xr zip_source_function 3
.Sh HISTORY
.Fn zip_source_seek_compute_offset
was added in libzip 1.0.
.Sh AUTHORS
.An -nosplit
.An Dieter Baron Aq Mt dillo@nih.at
and
.An Thomas Klausner Aq Mt tk@giga.or.at
